The present invention relates to an air intake device for an internal combustion engine comprising a main body and a cover element which are securely joined to one another and which form at least two intake pipes.
British Patent no. GB 2,279,035 discloses an air intake device comprising a main body having a cover element placed thereon and attached thereto by friction welding. The cover element is formed by four partial shells of the intake manifold, which are rigidly connected to one another via a transverse section of the header pipe. In order to be able to compensate for tolerances between the main body and the cover element, the material of the cover element is more flexible than that of the main body. However, the use of a flexible material for the entire cover element leads to a lower compressive strength of the intake manifolds. In addition, the use of different materials for the cover element and the main body may lead to a lower strength of the friction weld bond.
It is an object of the present invention to provide an improved air intake device of the foregoing type.
Another object of the invention is to provide an air intake device having a main body and a cover element which can be joined to each other with great precision.
A further object of the invention is to provide an air intake device which avoids the need for parts constructed of different materials.
These and other objects have been achieved in accordance with the present invention by providing an intake device for an internal combustion engine comprising a main body and a cover element which are securely joined to one another and which form at least two intake pipes, in which the cover element comprises a plurality of individual shells connected to one another, each individual shell forming a wall section of an intake pipe of the intake device, and wherein the connection between at least two successively adjacent individual shells is formed by a flexible connection element arranged between them.
The arrangement of a flexible connecting element between neighboring individual shells allows the compensation of tolerances between the main body and the cover element, such as those which may occur through contraction during injection molding, for example. The individual shells of the cover element are connected to one another as in prior devices, so that the number of individual parts is not increased. The cover element and the main body may be made of the same material.
The connection element is advantageously flexible in all three spatial directions, so that tolerances may be compensated for in all directions. For this purpose, the connection element has a flexible section, which is particularly positioned centrally between two individual shells. The flexible section may, for example, be produced easily in the injection molding method and has elastic properties, through which the tolerances may be compensated. In order to achieve approximately constant stress ratios, the flexible section has an approximately constant width over its length. The flexible section may advantageously be constructed, for example, as V-shaped, horseshoe or omega-shaped, circular, elliptical, or zig-zag shaped. Other configurations may also be advantageous.
To facilitate the ability, of the cover to accept and withstand applied forces, additional sections, which are thicker the flexible section, are provided between the individual shells and the flexible section.
The cover element is advantageously manufactured in one piece. The main body and the cover element may be connected to one another by a material bond, in particular by a vibration-welded joint. For this purpose, the main body and the cover element advantageously contact each other through peripheral flanges which can be welded together.
The connection element advantageously extends essentially in the plane of the flange of the cover element. The connection element is preferably fixed on the flange. In order to achieve good elasticity of the connection element, the thickness of the connection element is less than the thickness of the flange. Particularly in intake devices for internal combustion engines having large piston displacements, it may be advantageous for the individual shells to be rigidly connected to one another at one end, via a section of a collecting chamber, for example, and for at least one flexible connection element to be arranged at their other ends. In order to compensate for larger tolerances, it is particularly advantageous to arrange a flexible connection element between each pair of individual shells.